The TNIV website (and others) have this reading plan exploring how we should be involved in social justice. I think it's pretty good:
Two Weeks on Social Justice
Day 1: Exodus 3 - God hears the cries of the slaves.
Day 2: Leviticus 25 - The year of jubilee, a time of economic revolution.
Day 3: Ruth 2 - A poor woman finds help.
Day 4: 1 Kings 21 - Elijah speaks to a land-grabbing, murderous king.
Day 5: Nehemiah 5 - Nehemiah demands justice for the poor.
Day 6: Isaiah 5 - Warning to fun-loving materialists.
Day 7: Isaiah 58 - Worship that God appreciates.
Day 8: Jeremiah 34 - Freedom for slaves.
Day 9: Amos 2 - Sins against God by his own people.
Day 10 Amos 6 - Warning to the complacent.
Day 11: Micah 6 - What the Lord requires.
Day 12: Luke 3 - John the Baptist tells how to prepare for Jesus.
Day 13: Matthew 6 - Jesus speaks on material things.
Day 14: James 2 - How to treat the rich and the poor.